The present invention generally relates to a breakable link for use in a fishing line which breaks upon application of a load in excess of a terminal material failure of the breakable link. More particularly, the present invention relates to a breakable link configured to reliably break when a large animal such as a cetacean is entangled in the fishing line equipped with the breakable link, thereby releasing the animal without harm or death, or only with minimal injury.
It has been known in the fishing industry that whales and other cetaceans may be entangled in various underwater obstructions, such as fixed fishing gear, crab traps, sink gillnets, lobster trawls, and the like. More particularly, these animals may become entangled with buoy lines connecting a surface buoy at the water surface level to underwater gear located at the sea bottom. If the entanglement happens, the animal is likely to attempt to tow the surface buoy, buoy line and the underwater gear associated with the surface buoy. The heavy weight of the underwater gear, as well as the drag resistance from movement of the gear through the water, limits the ability of the animal to maneuver and/or resurface for air. The size and strength of the animal lets it continue for a limited time but under great strain and stress. In some cases, the animal may be severely injured and/or stressed which can lead to death of the animal.
Certain federal legislation, such as NMFS, has been passed to impose strict standards on the fishing industry to protect marine mammals from death or injury caused by entanglement with underwater fishing lines. A solution has been proposed to timely disconnect the underwater gear from the surface buoy, thereby releasing the entangled whale/cetacean from the buoy line attaching the two devices. In order to carry out this method, there is still a need for a device which, when incorporated in a fishing line, will reliably break to separate the buoy from the gear and free the entangled animal.
It is, therefore, an object of the present invention to provide a light weighted and inexpensive breakable link which, in practice, reliably breaks upon application of an appropriate load regardless of how, e.g., under what angle the load is applied to the breakable link.
It is another object of the present invention to provide a breakable link which can be used with a wide variety of rope or cable of different sizes without significantly affecting the breakable link""s capability of releasing an entangled cetacean from a underwater fishing line utilizing the breakable link.
It is a further object of the present invention to provide a breakable link configuration which facilitates calibration of the breakable link to various load requirements without having to scale up or down the whole device, thereby simplifying the manufacturing process.
These and other objects of the present invention are achieved by a method of establishing a fishing line, comprising the steps of a) providing a breakable link having two distinct attachment openings having walls joined to each other by a join portion; b) attaching the attachment openings to a surface buoy and underwater gear, respectively, using e.g. rope; and c) disconnecting the surface buoy from the underwater gear by irrecoverably breaking the wall of one of the attachment openings at a weakened portion thereof without breaking the join portion. In accordance with the present invention, it is desirable that at least one of the ropes used to attach the breakable link to the surface buoy and underwater gear is released without any portions of the breakable link staying on the rope.
In accordance with an aspect of the present invention, a break-away connector is provided for use in the method of the invention. The break-away connector comprises, along a longitudinal axis thereof, two connecting portions for connection with external devices, and a join portion joining the connecting portions together. One of the connecting portions is formed as a loop shaped body extending continuously circumferentially for 360xc2x0. The body comprises a first portion joined to the join portion, and a second weakened portion extending for about a half of an entire circumference of the body and having a material failure load smaller than those of the first portion, the other connecting portion and the join portion. Upon administration to the weakened portion of a load higher than the material failure load thereof, the body irrecoverably breaks at the weakened portion to disconnect the external devices.
In a preferred embodiment, the thickness and/or material failure load of the weakened portion is from about 50 to about 70% of the thickness and/or material failure load of the first portion, the other connecting portions and the join portion. For certain types of underwater gear, such as lobster trap, the material failure load of the weakened portion is preferably from about 500 to about 600 lbs. For other types of underwater gear and/or application, other strengths may be needed. The material failure load of the weakened portion is preferably in a range of from about 100 to about 3780 lbs.
In accordance with another aspect of the present invention, a fishing line is provided for implementing the method of the present invention. The fishing line comprises underwater gear, a surface buoy connected to the underwater gear via a buoy line, and at least a breakable link incorporated in the buoy line. The breakable link comprises, along a longitudinal axis thereof, two connecting portions for connection with external devices, and a join portion joining the connecting portions together. One of the connecting portions are formed as an annulus having a circular cross-section and extending continuously circumferentially for 360xc2x0. The annulus comprises a first portion joined to the join portion, and a second weakened portion having a cross-sectional diameter, and hence area, smaller than that of the first portion. Upon administration to the weakened portion of a load higher than a material failure load thereof, the annulus irrecoverably breaks at the weakened portion to disconnect the buoy from the underwater gear.
In a preferred embodiment, the cross-sectional diameter or area of the weakened portion is from about 50 to about 60% of the cross-sectional diameter or area of the first portion to ensure reliable break of the weakened portion. Preferably, the weakened portion extends circumferentially for from about 150xc2x0 to about 210xc2x0.
The connecting portions may be integrated with the join portion into a single body. Alternatively, the connecting portions are separately formed and pivotably attached via the join portion so that the connecting portions are rotatable with respect to each other about the longitudinal axis of the break-away connector while remaining inseparable along the longitudinal axis.